Ultrasonic method for cleaning teeth

ABSTRACT

A method for cleaning teeth by providing bursts of ultrasonic mechanical vibration at an applicator repeated at a sonic frequency to produce both ultrasonic and sonic vibratory motion and effect during use of said applicator.

United States Patent 1191 1 1 3,828,770 Kuris et al. Aug. 13, 1974 [54]ULTRASONIC METHOD FOR CLEANING 32/66, 50

TEETH [75] Inventors: Arthur Kuris, Riverdale; Lewis [56] Referencescued Balamuth, Southampton; Manuel UNITED STATES PATENTS Karatjas, GlenOaks, of 3,335,443 8/1967 Parisi et a1. 128/62 A 1 2 211251 1/122211:1:1:1 122/252 Farmmgdale, 3,547I110 12/1970 Balamuth 128/24 A [22]Filed: Dec. 26, 1972 [21] pp NO 318 428 Primary Examiner-Lawrence W.Trapp Related US. Application Data [57] A R n ation-impart of Ser. No.119,298, Feb. 2 A method for cleaning teeth by providing bursts of ul-1971' and a commuanonm'part of 2091971 trasonic mechanical vibration atan applicator re- 1971' I peated at a sonic frequency to produce bothultrasonic [52] U 8 Cl 128/62 A 32/50 and sonic vibratory motion andeffect during use of 51 rm. c1 A6lh 7/00 apphcato" [58] Field of Search128/24 A, 62 A; 32/65, 0 Cl ims, 22 Drawing Figures F O R C E U LT R A 5ON I C M E C HA N 1 CA L V B R AT l 0 N l 7 37; 27, 57; T1 2 Z- 2PAIENIEDMIBI 312m SHEET 1 IF 9 F G. FMECHANICAL VIBRATION AMPLITUDE I IfII III III W I ULTRASONIC MECHANICAL VIBRATION PATENIEU 31974 3.828.770

SHEU 5 BF 9 PATENIED 1mm 31914 770 sum 1 OF 9 Am V PAIENIEB mm 31914SHEU 9 BF 9 NNN ULTRASONIC METHOD FOR CLEANING TEETH CROSS-REFERENCE TORELATED APPLICATIONS This application is a continuation-in-part of ourcopending patent applications, assigned to the assignee of the presentinvention, Ser. No. 119,298 filed Feb. 26, 1971, entitled ULTRASONICKITS AND MOTOR SYSTEMS, and a continuation-in-part thereof, Ser. No.209,971, filed Dec. 20, 1971, entitled ULTRASONIC DENTAL AND OTHERINSTRUMENT MEANS AND METHODS, which entire subject matter of thecopending applications are incorporated herein by reference as if fullyset forth herein.

BACKGROUND OF THE INVENTION The field of the present invention residesin an electromechanical motor system in which the output applicatorthereof is made to vibrate intermittently at an ultrasonic frequency, toproduce bursts of ultrasonic mechanical vibrations repeated at a sonicfrequency. The motor system thus produced is capable of producingeffects characteristic of both ultrasonic and sonic vibratory devices.

Over the last decade a number of applications have been proposed andpatented in which the introduction of ultrasonic mechanical vibrationshas resulted in new and novel results. Towards this end the inventors ofthe present invention have pioneered in the development of ultrasonicmotor-converter systems that could be manufactured and incorporated intohome consumer products particularly where cost is a major consideration,as well as dental, medical, and industrial applications and uses.Towards this end the key consideration has been the development of a lowcost convertermotor system that would permit the application ofultrasonic energy for use as in an ultrasonic home dental unit,ultrasonic shaving unit and ultrasonic hobby kit to name but a few.These and other uses are indicated in the referenced co-pending patentapplications hereinafter referred to throughout the specification as theapplications for convenience. A method and apparatus for the ultrasoniccleaning of teeth is disclosed in U.S. Pat. No. 3,375,820 which issuedon Apr. 2, 1968 to Arthur Kuris and Lewis Balamuth while an ultrasonicmethod and apparatus for shaving is disclosed in U.S. Pat. No.3,610,080, which issued on Oct. 5, 1971 to Arthur Kuris. The entiresubject matter of said Letters Patent are incorporated herein byreference as if fully set forth herein.

The present invention provides for the first time a motor-convertersystem with a minimum number of electronic components that enables themanufacture, in the low power range of, for example, from 1 to watts, ofinstrumentation for home and other use which combines the beneficialeffects of vibrations in the ultrasonic range, defined herein to includevibrations in the frequency range of 10,000 Hz to 1,000,000 Hz, and inthe low sonic frequency range, defined herein to include vibrations inthe frequency range at 10 Hz to 1,000 Hz.

The inventors have discovered that there'are many instances where it isdesirable to produce a mechanical vibration which in effect is a seriesof high frequency vibration bursts separated by predetermined timeintervals, the separating time intervals being large compared with thetime intervals for a period of the high frequency vibration. Suchmechanical vibration is capable of producing all the necessary highfrequency effect essential to ultrasonic motor technology. However, thepulsing effect imparts to the motors applicator a kind of jiggling orbuzzing effect during use. Among other advantages to this specificresult of the double frequency system herein described is found in thefact that the buzzing action of the applicator during use gives the userthe psychological assurance that the system is doing its job.

This signalling of the presence of the operating condition of the devicehas been found to be necessary in consumer devices such as hobby kits,razors, toothbrushes and the like using ultrasonic vibrations forproducing their respective operative effects. In the prior art hand heldultrasonic devices, the user feels no difference in sensation in thehand holding the device when the device is on and when the device isoff. To be sure, visual aids may be used, such as a small pilot light,or an auxiliary sonic device to help the user know the device is on, butsuch aids add expense tothe device which is unnecessary and iseliminated by the simplicity of the solution to this problem disclosedherein. Further, not only is the foregoing problem solved by thearrangement in accordance with the invention, but further desirableoperative effects are produced in at least some of the ultrasonicdevices in question.

Thus, the arrangement in accordance with the invention produces thecompletely unexpected results of a low frequency macro-massage typeaction, simultaneously with the ultrasonic micro-massage and otheruniquely ultrasonic effects (due to cavitation, etc.) normally expectedfrom the ultrasonic devices in question. One of the most importantconsequences of the invention is the establishment of a uniquely newmethod for applying ultrasonic energy to tissues with the synergisticbenefit of simultaneous micro-massage and macromassage.

A further unexpected beneficial result of the method and devices inaccordance with the invention is the dramatic improvements in theapplication of ultrasonic energy for periodontal procedures, primarilyfor use in the home. Ordinary toothbrushing uses bristles and toothpaste to keep tooth surfaces clean and hopefully, polished and bright, acondition usually characterized as whiten. In addition, an attempt ismade to clean out interproximal, gingival crest, or gumline areas, andother hard-to-get-at areas without too much success. Conventional dentalteaching requires the toothbrusher to learn how to stroke thegingival-tooth boundaries so as to provide some gum stimulation.Electric-vibratory, i.e., cycle per second, toothbrushes attempt to meetall the above goals with greater efficiency and with the aid of outsideelectrical energy to provide additional motion to the bristles duringuse. However, such electricvibratory toothbrushes merelyv utilize theprinciples of conventional toothbrushing. Recently, dental science hasrecognized the need for the removal of plaque during home periodontalcare as an assist to the professional care ordinarily supplied by thedentist. However, conventional home cleaning devices used in aconventional manner fail to remove plaque.

The inventors have discovered that the addition of high frequencymechanical vibration energy to such elements as bristles or Stimudentsor other applicators permits the removal of plaque, thereby extendingthe benefit in oral hygiene normally obtained from the dentist to safeself-administered procedures followed by the patient at home. As isusual with high frequency mechanical vibration devices the benefits aremultivalued comprising the possibilities of micro-massage, fatiguedestruction of calculus, interproximal cleaning due to cavitationalenergy in associated fluids being present, and the like.

The inventors have now found that the utilization of two frequencies ina vibratory system has produced unexpected beneficial effects, with eachfrequency performing its function such that the cummulative effect ofthe utilization of two frequencies exceeds the beneficial effect ofeither frequency working in its own frequency range. For example, withrespect to the brushing or cleaning of teeth, it has been establishedthat the high frequency energy is capable of removing plaque from theteeth with the low frequency introducing a macro-massage type actionboth on the gums and also cleaning teeth with respect to the effect thatthe low frequency range provides. Similar benefits are obtained in thefield of shaving where the high frequency of vibratory energy plays itsrole as more particularly described in US. Pat. No. 3,610,080, and thelow frequency component produces its own beneficial effect.

Aside from the ability for the first time to simultaneously utilize thebeneficial results of two known frequency ranges in a single instrument,the arrangement and method in accordance with the invention producesresults obtainable due to the combined effect of the two frequencies.Accordingly, the motor-converter system of the present invention may beutilized in such a manner that work may be performed on an object suchthat it may operate at an ultrasonic frequency and an audible frequencysimultaneously with said ultrasonic vibrations. Since the current bestultrasonic motor art requires the vibration frequency of the motor to beat or near one of the natural vibration resonance frequencies of themotor, the current invention may use an automatic frequency controlfeedback circuit which guarantees a selection of the desiredaforementioned resonant mode.

SUMMARY OF THE INVENTION Generally speaking, in accordance with theinvention, a method for performing work on a object is providedincluding the steps of positioning an applicator capable of physicalvibration at an ultrasonic frequency adjacent the object, inducingvibrations in said applicator at a frequency in the ultrasonic range andmodulating the ultrasonic frequency of said applicator at a sonicfrequency so as to produce spaced bursts of ultrasonic vibration in saidapplicator. To remove foreign matter including plaque and other surfacedeposits from teeth, the method in accordance with the invention wouldconsist of the steps of positioning adjacent the teeth to be cleaned aplastic surface capable of supporting and transmitting ultrasonicvibrations, vibrating said surface in spaced bursts of vibrations in theultra sonic frequency range, said bursts being repeated at a sonicfrequency, and moving said vibrating surface relative to said teeth sothat it engages and removes the deposits therefrom. Said surface is inthe form of a plurality of individual bristle elements such that theelements assume positions in which they are randomly di- 4 vided betweenactual contact with and displacement from thesurface of the teeth. Afluid film may be provided at the teeth surfaces.

Shaving hair by'the method in accordance with the invention includes thestep of generating ultrasonic vibrations in the cutting edge of a bladecoupled to a hand-held ultrasonic motor, applying bursts of ultrasonicvibrations at said cutting edge, said bursts being repeated at a sonicrate, and engaging said cutting edge adjacent the hair to be shaved in arelative moving relationship.

The systems in accordance with the invention include vibratory meanscapable of physical vibration at an ultrasonic rate and driving circuitmeanselectrically coupled to said vibratory means for applying a drivingsignal to said vibratory meansfor sustaining the vibration thereof, saiddriving signal consisting of ultrasonic portions repeated at an audiorate to produce bursts of ultrasonic vibrations in said vibratory meansrepeated at said audio rate. Said vibratory means may include atransmission member having an output and at which said vibrations areproduced and transducer means physically engaging said transmissionmember and electrically coupled to said driving circuit means. Saidvibratory means may define an ultrasonic motor mounted in an ultrasonicinstrument means adapted to be hand held by the user thereof.Interchangeable means may be provided adapted to be secured to the frontend of the ultrasonic instrument means to permit a variety ofapplications of ultrasonic mechanical vibrations to a selected objectfor various results. Said interchangeable means may be in the form of arazor, a toothbrush or the like. The driving circuit means may includeoscillator circuit means for producing a signal at said ultrasonicfrequency and modulating circuit means coupled to said oscillatorcircuit meansfor modulating said ultrasonic frequency signal at a sonicfrequency to produce said driving signal. Said ultrasonic motor may becapable of vibration at a plurality of ultrasonic frequencies includinga desired frequency, and said driving circuit means may include tunedcircuit means tuned to said desired frequency for controlling thefrequency of said driving signal and means for applying a detectedsignal representative of the frequencies of vibration of said ultrasonicmotor to said tuned circuit means, the tuned circuit means responding tothe desired frequency portion of the detected signal to cause saiddriving circuit means to produce a driving signal of the desiredfrequency.

OBJECTS OF THE INVENTION A primary object of the present invention is toprovide a variety of ultrasonic converter systems having both ultrasonicand sonic frequency characteristics adaptable for both consumer andcommercial use.

Another object of the present invention is to provide an ultrasonicsystem wherein bursts of ultrasonic vibrations are produced at anapplicator, said bursts being repeated at an sonic frequency.

Still another object of the invention is to provide an ultrasonicmotor-converter system incorporating interchangeable accessoriespermitting a wide variety of uses.

A further object of the invention is to provide a new and novelultrasonic motor-converter system.

Still another object of the invention is to provide a new and novel dualfrequency driving circuit for ultrasonic devices.

Another object of the present invention is to provide a new and novelmethod of applying ultrasonic mechanical vibrations.

Still another object of the present invention is to provide improvedmethods and apparatus for performing oral hygienic procedures withultrasonic energy.

A further object of the present invention is to provide novel andimproved cleaning techniques for personal oral hygienic care whichenables the user to control and obtain significantly better cleaning ofteeth.

Still a further object is to provide new and novel methods and apparatuswhich are embodied in a device that is completely safe for use by adultsand children in the home on a regular basis.

Another object of the present invention is to provide new and novelmethods and apparatus for regular personal oral hygienic care whichprovides excellent cleaning results in the hard to reach interproximaland gumline areas in general, and simultaneous gum stimulation.

Still another object of the present invention is to provide improvedcleaning techniques for the removal of plaque, tartar, calculus,stubborn stains and interproximal soft debris.

Another object'is to provide an ultrasonic oral hygene device providinga sensual indication of its operation during use.

A further object of the present invention is to provide methods andapparatus employing ultrasonic and sonic energy simultaneously forshaving of skin and which is completely safe for use in the home.

Still a further object of the present invention is to provide novelforms of shaving apparatus and improved shaving techniques employingsonic and ultrasonic energy in which the frictional resistance tomovement of the shaving instrument over the skin is substantiallyreduced.

Another object of the present invention is to provide a novel andimproved shaving technique and apparatus employing sonic and ultrasonicenergy which may be employed with or without a shaving cream.

Still another object of the present invention is to provide anultrasonic shaving apparatus providing a sensual indication of itsoperation during use.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification anddrawings.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, and theapparatus embodying features of construction, combinations of elementsand arrangement of parts which are adapted to effect such steps, all asexemplified in the following detailed disclosure. and the scope of theinvention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS Although the characteristic featuresof this invention will be particularly pointed out in the claims, theinvention itself, and the manner in which it may be made and used, maybe better understood by referring to the following description taken inconnection with the accompanying drawings forming a part hereof, whereinlike reference numerals refer to like parts throughout the several viewsand in which:

FIG. 1 is a diagrammatic view of the waves of the ultrasonic frequencypattern;

FIGS. 2a and 2b are diagrammatic views to illustrate the theory of thepresent invention in which two frequency components are employed;

FIG. 2c is a fragmentary view of an element vibrated in accordance withthe invention and its interaction with a surface;

FIG. 3 is a view of an electrical circuit of the invention to obtain thedual frequency;

FIG. 4 is a perspective view of an ultrasonic home oral unit inaccordance with the present invention;

FIG. 5 is a front view of the ultrasonic home oral unit in accordancewith the present invention;

FIG. 6 is an end view of the ultrasonic home oral unit in accordancewith the present invention;

FIG. 7 is a side view in cross-section of the ultrasonic home oral unitin accordance with the present invention;

FIG. 8 is an enlarged sectional view of a portion of the unit in FIG. 7;

FIG. 9 is an enlarged sectional view of a portion of the unit in FIG. 7;

FIGS. 10-13 illustrate the cleaning system of the present invention inrelation to a set of human teeth and are helpful in explaining theprocess of the instant invention;

FIG. 14 is a view of an electrical circuit similar to that discussed inFIG. 3 but of another form of the invention;

FIG. 15 is a view of another form of electrical circuit in accordancewith the invention;

FIG. 16 is a perspective view of the invention as used for shaving;

FIG. 17 is the shaving apparatus in relation to the skin of the user;

FIG. 18 is a fragmentary side elevational view of the head portion of afurther embodiment of the home oral unit in accordance with the presentinvention;

FIG. 19 is an end view of the home oral unit in FIG. 18; and

FIG. 20 is a further side elevational view of the home oral unit in FIG.18 with the housing in cross-section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings indetail, and initially to FIGS. 1, 2a, 2b and 2c, the theory relating tothe present invention in which two frequency components are employed ina mechanically vibrating ultrasonic motor will be described. In the art,ultrasonic motor-converter systems are generally adapted to producemechanical vibrations in the form of a continuous, simple harmonicvibration of constant amplitude, as depicted in FIG. 11, waveform 10having a constant vibration amplitude 11 and a period of oscillation 1'These ultrasonic vibrations generally lie in the frequency rangeincluding 10,000 Hz to 1,000,000 I-Iz. One characteristic of suchultrasonic vibrations is that a solid surface vibrating at an ultrasonicfrequency is actually felt in a different way than when the surface isnot vibrating. During ultrasonic vibration, friction between the solidvibrating surface and an object placed in engagement therewith isdrastically reduced, in large measure due to the acceleration f thevibrations, which in the case of ultrasonic vibrations, is at least1,000 g.

The inventors have now discovered that in many in stances, it isdesirable to produce a mechanical vibration of the type shown in FIG.2a, which consists of a series of high frequency vibration bursts l2separated by equal time intervals 14, said separating time intervalsbeing large compared with the time interval 13 representing the periodof the high frequency vibration (1 As is apparent from an examination ofFIG. 2a, the bursts of high frequency vibration are defined by half sinewave envelopes, the width of each envelope being equal to time interval14. Bursts of high frequency vibration 12 are repeated at a sonic or lowfrequency having a period 1' For an ordinary l volt 60 cycle A.C. sourceof voltage, 1' would correspond to one-sixtieth see. If the naturalresonant frequency of the high frequency vibration is 30,000 Hz, T isl/30,000 sec. Expressed in microseconds, T2 would equal 33.4 ,a sec. and7, would equal 16,000 usec. The frequency of repetition of the bursts ofhigh frequency vibrations lies in the sonic range, and more particularlybetween 10 Hz and 1,000 Hz In the example given, each burst of highfrequency vibration would include as many as 5,000 completereciprocations.

It has been found that when an electro-mechanical transducer orultrasonic motor is vibrated as indicated in FIG. 2a by bursts orpackets of ultrasonic vibrations, the user experiences adefinitephysical sensation when an applicator mounted on said transduceror motor is engaged against a surface. This sensation, described asbuzzing or jiggling permits the user to distinguish between theconditions during which the applicator is on and when said applicator isoff. The drastic reduction in friction caused by ultrasonic vibrationsprevents the experience of any such physical sensation when a prior artultrasonic applicator is used. The buzzing or jiggling appears to occurat the sonic or low frequency and is believed to be caused by thedifference in the frictional forces between the applicator and thesurface engaged by the applicator during the bursts of ultrasonicvibration and in the interval between such bursts. Specifically, duringultrasonic vibrations, friction between the ultrasonic applicator andthe surface is drastically reduced as compared with the friction duringthe interval between said bursts. The resulting, alternating slip-stickeffect between the applicator and surface is believed to cause saidbuzzing orjiggling. The forces at work when an applicator is vibrated inaccordance with the invention as depicted in FIG. 2a is indicated by aconsideration of FIGS. 2b and 2c. In FIG. 2b, the lower waveformrepresents the actual ultrasonic mechanical vibration of an applicator,such as toothbrush bristle 2 mounted on a vibrating head 3 ,whenengaging against a tooth or gingival surface 4.

The ultrasonic vibrations within each burst is in the directionrepresented by double-headed arrow 5.

Each burst of ultrasonic mechanical vibration lasts for a half period (1/2) of the sonic modulation frequency. In an actual device, during theinterval b between bursts the device would be vibrating at an ultrasonicfrequency, but at a very low amplitude. During interval a. thefrictional force of the bristle 2 against tooth 4 is reduced resultingin a slipping action. However. at the same time. during each individualhigh fre quency reciprocation there is animpulsive force represented inthe upper waveform of FIG. 2b. This impulsive force pulls on thesurrounding liquid (saliva, mouthwash, dentifrice, or whatever-fluid ispresent,) and cavitation results. Each returning pushing force in theliquid causes the cavities to collapse with consequent production ofshock waves. All of this action is rapidly repeated during intervals a.The dynamics of the force present in interval a is extremely complex,the representation in FIG. Zhbeing intended as schematic and suggestiveof the forces present. During intervals h, we have a relative period ofrest, insofar as high frequency vibration is concerned. The reduction infrequency is dependent on the presence of relative high amplitudeultrasonic vibrations, the low amplitude vibrationspresent duringinterval 12 not being sufficient to reduce the frequency, and a suddenrise in frictional force occurs. This sudden rise in frictional force isrelated to the ordinary brushing force represented by arrow 6 in FIG. 20which would be present if the brush a were used with no high frequencyvibration at all, and results in the normal displacement of the brush bythe user. This sudden rise in brushing force occurs as the highfrequency vibration force disappears and will continue during theinterval b, which can be characterized as a stick interval. Thus, due tothe stick-slip effect of the alternating sonic modulation of the highfrequency vibration, a succession of force peaks 7 is produced. Ineffect, this is somewhat like the introduction of a sonic tapping of thetooth gingival structure, the tapping frequency corresponding exactly tothe sonic modulation frequency (1/1- Thus, the method and apparatus inaccordance with the invention subject the surface engaged by theultrasonic applicator, and in this case, the teeth and gums to a complexseries of dynamic actions incorporating both sonic and ultrasonicfrequencies of energy. During each interval a, an ultrasonic quanta ofenergy is applied, while during each interval b, a peak of energyrepresentative of the brushing force is applied. Since the brushingforce peaks and the. ultrasonic quantas of energy alternate at a sonicrate, it may be said that the method and apparatus in accordance withthe invention produces successive time periods of high frequency and lowfrequency effects. As used herein, the term simultaneously", as appliedto these effects, merely refers to the fact that during a fraction of asecond, both effects are repeated many times. Thus, for a Hz sonicmodulation frequency, there would be in one-tenth of a second, thousandsof reciprocal high frequency actions and 10 low frequency actions. It isthis unique set of actions which produces the synergistic results, oneof which is the rapid and complete removal of plaque from teethincluding the interproximal regions, together with macroandmicro-massage of the gingival tissues. A further effect is the buzzingor jiggling sensation experienced by the user. In addition, all of thenecessary high frequency effects essential to ultrasonic motortechnology are produced during the bursts of high frequency vibration.

Referring now to FIGS. 3-9, an embodiment 20 of the arrangement inaccordance with the invention is depicted including an instrument means25 in combination with driving circuit means 30 that work together inunison to perform a variety of applications, as for example that oftoothbrushing. The embodiment 20, for example, is designed to permitdaily use by a person in the home of a toothbrush, the bristles of whichare ultrasonically vibrated in bursts repeated at a sonic frequency. Inthis embodiment, the sonic frequency is 60 Hz, and while the toothbrushis effective for the removal of plaque, which is generally recognized asa principal source of calculus formation and possible subsequent loss ofteeth due to periodontal disease, and stimulation of the gingiva,especially at the toothgingiva junction regions, the total power levelintroduced into bristles 38 is considerably less than 1 watt. It isnoted that the ultrasonic vibration of bristles 38 is invisible to thenaked eye.

Instrument means 25 includes handle means 26 adapted to be hand held bythe user in a conventional manner, and also has a detachable applicatormeans or assembly 35 containing a bristle cluster or stimulent 38 to beultrasonically vibrated. Extending from one end of instrument 25 issupply means 32 in the form of an electrical cable for transmittingpower, in the form of a driving signal from driving circuit means 30 toinstrument means 25. Driving circuit means 30 is mounted within acabinet 130, and power for said driving circuit means may be obtainedfrom a standard electrical outlet (a 60 Hz A.C. source) by-means ofelectrical cord 134 terminating in plug 132. A switching means 40 ismounted on cabinet I30 consisting of a switch 42 connected in the powerline for the selective energization of the ultrasonic transducer ormotor 45 contained within the housing defining handle means 26. Supplymeans 32 consists of a flexible conduit 52, through which leads 44, 46,48 and 100 extend. Line 44 is a separate grounded cable connected to theground of the electrical outlet plug. The ultrasonic mechanicalvibrations of bristles 38 as indicated by arrow 41.

Driving circuit means 30 is preferably of the solid state type and mayhave a-power rating of as small as l to 4 watts, and is generally withinthe range of l to watts. The actual mechanical power delivered to thebristles and subsequently to the gingiva and teeth of the user isvariable depending on the pressure and movement of the bristles by thehand of the user. In the case, the power under maximum conditions is buta minute fraction of the power delivered to the motor 45.

Essentially, ultrasonic motor 45 as hereinafter described is designed,depending upon the use thereof, to

- accept a variety of applicator means 35 and the magnitude ofultrasonic mechanical vibrations to be imparted thereto may be selectedby proper motor design. The motor 45 includes a transmission member 50which has a rear section 54 and front section 56, which may of circularcross-section, with a counterbore or seat 58 extending from its rearface 60 to a bottom surface 62. Mounting means 65 is provided andincludes a radial seat 66 adapted to contain therein means as in theform of an O-ring 68.

The transmission member 50 has a contoured-radius connecting portion 70connecting together the front section 56 and the rear section 54 of thetransmission member 50, which sections may both be of circularcross-sectional area. The front section 56 extends out beyond the frontend 74 of the tubular housing 72 a sufficient distance. The motormounting means, although illustrated to be in the form of an O-ring 68,may take other forms and shapes as desired.

'The ultrasonic motor 45 in conjunction with the applicator means 35 islongitudinally dimensioned so as to have lengths which are generallywhole multiples of half-wavelengths of the compressional wavesestablished therein at the resonant frequency of the combinedlongitudinal length of the components so that longitudinal loops orother components of motion occur at the end 78 of the applicator means35. Thus, the optimum amplitude of longitudinal vibration andhyperaccelerations of transmission is achieved, and such amplitude isdetermined by the relationship of the masses of the rear section 54 andthe front section 56 which may be made effective to either magnify orreduce the amplitude of the vibrations received from the transducercrystal. In the usual case, transmission member 50 serves as anamplifier. The front section 56 may be permanently attached toapplicator means 35, or the front section 56, or part thereof, may beprovided with a threaded stud 160 adapted to be screwed into a tappedhole 162 in the end of the transmission member 50 for effecting rigidconnection of the applicator' means 35.

A piezoelectric element such as crystal 80 is mounted within the cavitymeans 58 of the rear section 54 and it may be of tubular shape and inthe embodiment shown comprises a lead zirconate-lead titanate ceramiccrystal which is formed so as to be capable of ultrasonic vibrationalactivity in its longitudinal direction when activated by high frequencyelectrical impulses delivered to it as will be desired.

The crystal 80 is mechanically joined by a hardening cement 82 of, forexample, the epoxy type which, upon setting, becomes rigid and providesa solid direct mechanical coupling between the front end portion 84 ofcrystal 80 and rear section 54 of transmission member 50 so thatultrasonic longitudinal vibrations of the latter are directlytransmitted to said rear section 54 to form a compound resonator. Asshown in FIG. 9 the rear section 54 has a skirt portion 86 which extendsdownwardly over the front end 84 of crystal 80 and a recessed portion 58is provided to receive the epoxy cement 82 to circumferentially surroundthe front end of crystal 80.

Crystal 80 is provided with an electrically conductive silver coating 92on the inner wall 88 thereof of approximately 0.0015 inch in thickness.Conductive coating 92 may extend along the entire length of said innerwall 88 or within one-fourth inch of the end of said inner wall. Asimilar silver coating is formed on outer wall of crystal 80, the latterconductive coating being in two sections, a main section 93 extendingalong all of surface 90 of crystal 80 except for the end regionsthereof, and an annular portion 96 on the rear portion of outer wall 90,separated from main portion 93 by a gap 98. Such coatings may be appliedby electro-deposition or any other conventional process. Driving circuitmeans 30 is electrically connected with ultrasonic motor 45 by means ofleads 44, 46, 48 and 1100. Lead 44 is soldered to end wall 62 of rearsection 54 of transmission member 50 to specifically ground saidtransmission member. Lead 48 is soldered to conductive coating 92 whilelead 46 is soldered to conductive coating 93, conductive coatings 92 and93 cooperating to apply the driving signal to crystal 80. Finally, lead100 is soldered to the annular conductive coating 96, which, togetherwith a portion of conductive coating 92 defines a oscillation detectormeans.

A driving signal oscillating at the proper frequency delivered alongleads 46 and 48 to conductive coatings 92 and 93 from driving circuitmeans 30 will produce the desired piezoelectric effect and ultrasoniclongitudinal vibration of crystal 80 and applicator means 35.

THe ultrasonic vibrations are created in crystal 80 and transmitteddirectly to applicator means 35, so that when bristles 38 are applied toa tooth or other surface to be cleaned, the vibrations serve to performthe desired cleaning function. The vibrations are created in crystal 80by the expansion and contraction thereof in the longitudinal directionwhen excited by a high frequency electrical driving signal. The crystaland transmission member are specifically designed to be resonant at aparticular frequency, for dental applications, preferably about 35,000Hz. In fact, the ultrasonic motor depicted does not have a singlenatural resonant frequency mode of operation, but rather, has a wholespectrum of possible modes which include subharmonics and harmonics ofthe design operating mode frequency. It is preferable to design theultrasonic motor so that it oscillates at a frequency which will producethe highest Q. The Q at idle is selected to fall within the strainlimits of endurance of the motor. The motor is further designed for peakefficiency under load, i.e., when bristles 38 are engaged against thetooth and gingival surfaces of the user. If the loaded Q dropssignificantly below the Q of the other resonant modes of vibration ofthe ultrasonic motor, then, under load, the motor will hop out of tuneand vibrate at this other frequency. If this occurs, the device wouldbecome ineffective because the motor is not designed for efficientoperation in the new frequency mode. This problem is solved by theprovision of the detecting electrodes defined by conductive coating 96and the overlapping portion of conductive coating 92 and by the designof the driving circuit means 30 as will be more particularly describedbelow.

Crystal can be electrically energized, if desired, to have vibratorycomponents in other than the longitudinal direction to provide variousmechanical effects. This would be accomplished by changing theexcitation frequency. In addition, the location of application of thevoltage to the crystal can be utilized to produce different effects. Forexample, by applying the voltage across opposite ends of the crystal, attorsional effect is produced.

When driving circuit 30 is energized, as by closing power supply switch42, the sudden surge of current therefrom will drive crystal 80 into avibratory mode of operation. The vibrations of crystal 80 will in turninduce vibrations in the detector electrodes so that a signalrepresentative of the frequencies of vibration of the ultrasonic motor45 is transmitted back along line 100 to driving circuit means 30. Asshown in FIG. 3, said circuit includes a variable inductor and capacitor106 connected in series with line 100 to receive the detected feedbacksignals. Said inductor and capacitor define a tuned circuit which istuned to the design frequency of motor 45 so that, only the portion ofthe detected signal at the desired frequency is passed by said tunedcircuit. In effect, the tuned circuit serves as a filter, the filteredsignal of the desired frequency being applied to the base 104 oftransistor 102 which serves to amplify the detected signal. The emitter116 of transistor 102 is connected through resistor 118 to ground whilethe collector 114 is connected through primary winding 110 oftransformer 112 to line 124, which in turn is connected to a powersupply. This power supply consists of the normal AC. 60 Hz power supply,which is connected through lines 34 and 36, line 36 being grounded. Line34 is connected through switch 40 to diode which serves as a half-waverectifier of the A.C. signal. Lines 34, 36 are coupled by a capacitor122 which provides D.C. isolation and some minor smoothing. Theresultant, essentially half-wave signal is applied to line 124 tomodulate the ultrasonic frequency electrical signal applied to the base104 of the transistor. The resulting half-wave bursts of ultrasonicoscillation, said bursts being repeated at a 60 Hz frequency, areapplied to lines 46 and 48 through transformer 112 for drivingultrasonic motor 45.

Driving circuit 30 thus serves to sustain the ultrasonic vibrations of.motor 45 within each burst of vibrations at the desired'frequencythrough the mechanism of the detector electrodes and the tuned circuitdefined by inductor 120 and capacitor 106. Further, by modulating theultrasonic frequency oscillating signal by a halfwave rectified 60 Hzsignal, the desired bursts of ultrasonic vibration are produced. Whilethe embodiment of FIG. 3 depicts a driving circuit having an AC. powerline as a power source, the arrangement in accordance with the inventioncould also be driven by a battery, in which case a suitable sonicfrequency oscillator circuit would be provided for producing a half-wavesignal of a sonic frequency for modulating the ultrasonic frequencysignal applied to the base of transistor 104.

It will appreciated by one skilled in the art, that the entire drivingcircuit means can be formed from about eight components, a very smallnumber permitting the production of very compact and light weightdriving circuits. The precise values of the respective componentsdepends on the power output of the device. But,

as illustrated in FIG. 4, the driving circuit may be mounted in arelatively small housing 130. The components may easily be contained ina rectangular area having the dimensions 1 /2 X 2 X 1 /z". Switchingmeans 40 mounted on said cabinet permits the user to selectively turnthe toothbrush on or off as desired. Not only does the foregoingconstruction reduce size, it substantially reduces the cost thereof tothe point where a consumer product becomes feasible. As shownparticularly in FIG. 7, housing 72 may be injection molded or formed inan acceptable manner and includes a rear section plug 136 that fits intelescopic relation with the housing 72 and having an aperture 138extending axially therethrough for receiving flexible conduit 52 ofsupply means 32 to retain said flexible conduit in fixed positionrelative to plug 136. A clip 140 is positioned around conduit 52 toretain the latter such that the user cannot apply any tension on leads44, 46, 48 or l00during use of the instrument. A pin 142 is seen toextend through the wall of handle housing 72 and into a pocket in plug136 so as to retain the latter in fixed position. Various means may beused for this purpose. To retain the motor 45 in fixed position relativeto the housing 72, retaining means 145 may be employed. As seenparticularly in FIG. 9 the retaining means may include a dowel or pin146 that extends transversely through the housing wall 144 and into apocket or seat 148 contained within the rear section 54 of thetransmission member 50 so that the latter remains in fixed positionrelative to the housing 72 when the user either initially secures theapplicator means 35 to the instrument means 25 or removes it therefrom.Obviously, other forms of retaining means may be employed to maintainthe coupled relationship so that rotational movement is prohibitedbetween the transmission means 50 and the housing 72.

As seen particularly in FIG. 9, the front end 74 of the housing 72 mayhave a lip 150 that blends with the connecting portion 70 of thetransmission member 50. Mounting means 65, which also includes -ring 68,also acts to seal the inner chamber of the handle means 26 from anyfluid that might try to seep into the instrument during use by the user.

Applicator means 35 may take various forms, shapes and configurations,so long as it is designed so that the complete system will operate intune whether the instrument is out of engagement with any surface, suchas in the air, or in engagementwith a surface which may be the oralcavity of the user or may be the face of the user where the applicatormeans is a shaving device. The apparatus in accordance with theinvention is particularly adapted to maintain the combined ultrasonicmotorapplicator means vibrating at the desired frequency at various loadconditions, and to modulate such vibrations so as to produce bursts ofultrasonic vibrations. It is the ability to obtain and maintain thisvibratory condition with the combination of electronic circuitry andultrasonic motor which is a particular feature of the present invention.

The applicator means 35 in this embodiment of the invention isillustrated as an ultrasonic toothbrush which is more fully disclosedand described in a simultaneously filed co-pending patent applicationassigned to the assignee of the present invention and entitledUltrasonic Toothbrush Applicator, Ser. No. 318,430 which may be referredto for a more detailed discussion of a form of brush applicator that maybe used in connection with the present invention and reference theretomay be had for information, but by no means limitation thereto.Essentially, the brush applicator includes a body portion 152 having aplurality of bristle clusters 38 extending therefrom at substantiallyright angles thereto and terminating prior to the end face 78. The bodyportion 152 merges with a neck portion 154 and terminates at an end face156. Coupling means 160 is provided for proper transmission of theultrasonic and sonic vibratory energy from the end of front section 56of transmission member 50. Said transmission member has an axiallyextending tapped hole 162 which receives therein a threaded stud 164which merges with a flange portion 165, which in turn has a threadedportion 166 extending from the opposite end thereof in axial alignmentwith the threaded stud 164. The threaded portion 166 may be firmlysecured within complimentary threads 168 contained within the bodyportion 154, a bonding agent 170 being provided therebetween to helpcouple the energy between threaded portion 166 and the body portion 154.If coupling means 160 is injection molded in combination with theplastic applicator means 35, then the bonding agent can be dispensedwith since an intimate coupling between the' two threads is obtained andsufficient energy transmission is realized to properly transmit energyto vibrate the bristle clusters 38 which in turn produce the vibratingmotion in accordance with the invention. The flange portion 165 may beof a cross-sectional area such as hexogonal to permit ready grasp byeither mechanical means such as a wrench or by the hands of the user toassure that the bottom face 172 is in intimate contact with the outputend or front face 61 of the output section. An axial bore 174 may beprovided, if required, as to control the total cross-sectional area ofthe body portion 154 so as to obtain the proper transmission ofvibratory energy to the head portion 152 and in turn the bristleclusters 38.

To provide a protection for flange portion and the body portion 154, asleeve 175 may be shrink fitted as seen in FIG. 9 to properly encompassthe material which it covers. The sleeve 175 may be of a plasticmaterial and may also act as insulation.

Turning now to FIGS. 10-13, there is illustrated a portion of the dentalcleaning procedure in accordance with the invention in operativeposition in the oral cavity 178 against the teeth 180.

The brush construction may be that which resembles closely an ordinarymanually actuated toothbrush or designed more particularly as set forthin the copending patent application entitled Ultrasonic ToothbrushApplicator hereinabove referred. In accordance with the invention, thebrush bristles 38 of the applicator means 35 is positioned against theteeth 180 in the usual manner during the brushing operation. That is,the bristle clusters 38 are inserted in the mouth and positionedadjacent the tooth surfaces 183 with a relatively light pressure. Thebristle clusters 38 may be moved manually to pass the brush portionacross all of the tooth surfaces, the bristles 38 randomly assumepositions in contact with and displaced from tooth surfaces. Since inthe case of manual brushing, the bristle elements 38 rarely assumepositions such that they extend deeply into the interproximal areas thepresent brush is designed to approximate the curvature thereof.

In this manner the action between the sonic motion and ultrasonic motionis believed to result in a combination effect such that the beneficialfeatures of each frequency is simultaneously obtained.

Accordingly, the removing of plaque 181 on the tooth surface 183 andforeign deposits 182 are obtainable with the present invention. In FIG.10 plaque is shown as a coating that has adhered to the surfaces of theteeth 180. Plaque, a soft gelatinous substance produced in the mouth bythe action of salivary and subgingival bacteria, hardens into calculusin a period of from 2 to 12 days, and is believed to be a significantfactor in causing periodental disease.

In use, the bristle clusters 38 are vibrated in accordance with theinvention so as to introduce a micromotion and a macro-motion asdescribed above. When bristle elements 38 are lightly engaged againstthe teeth surface 183 and a relative moving relationship is maintainedthere is generated sufficient action to remove the plaque 181 andinterproximal deposits 182. This action is generally obtained byproviding a fluid film as illustrated by the particles 184 which may bein the form of a dentifrice having certain characteristics such as mildabrasive characteristics, water or simply that of saliva. The ultrasonicmotion at the bristle elements 38 is of sufficient amplitude ofvibration to also produce a cavitational action in the fluid film 184.

In addition, the present invention permits stimulation of the gingivaltissue by macro-massage and micromassage which has been found beneficialfor dental health, said massage also resulting in more blood circulationthan is obtained by conventional brushing techniques. In addition, thestick-slip effect produces a sonic audible vibration due to the tappingof the bristles against the teeth which helps the user psychologicallyby communicating to him the fact that the instrument is working.

. be applied to said applicator means. Furthermore, the

length and stiffness of the various bristles may be varied within theconfines of the present invention and beneficial results may still beobtained.

The bristle elements 38, .as seen particularly in FIG. 13, may have acontoured surface configuration that lead themselves to conform to thecontour of teeth 180 such that the bristle elements form a surfaceconsisting of a multiple number of pointed members interproximately ofthe teeth during the brushing thereof which produces peak accelerationsin the bristle elements.

One aspect of the present invention is to provide an insulated coating186 that may surround the toothbrush head 152 to improve efficiency inthat the coating 186 may be of a material which prevents transmission ofhigh frequency vibratory energy into liquid, teeth or gums. This isreadily accomplished, for example, with a closed cell rubber sheet 186.The closed cell layer 186 presents to the vibrating surface an acousticimpedance equivalent to that of an air film. The acoustic impedance ofair is so mismatched, i.e., so much smaller than the acoustic impedanceof the brush head plastic 152 that all ultrasonic energy waves arrivingat the brush head-closed cell interface will be almost totally reflectedback into the plastic thereby making more energy available to thebristle clusters 38 to do their work.

Referring to FIGS. 18-20, the instrument 220 depicted differs from theinstrument depicted in FIG. 3,

in that a cowling or hood 222 extends about the sides,-

rear and end of applicator means 35 so as to prevent engagement of saidapplicator means with the cheak or jaw of the user. Cowling 222 isformed integral with housing 224 as more particularly shown in FIG. 20.

Referring now to FIG. 14, the system a depicted is essentially identicalwith the system of FIG. 3, except that driving circuit 30a is providedwith a resistor 120a in place of variable inductor 120. Thisconstruction assumes that the ultrasonic motor 45 is designed so as tobe stable in its frequency of operation when subjected to normal loadsexperienced in toothbrushing, so that the tuned circuit arrangement ofFIG. 3 is not required. In all other respects, the arrangement of FIG.14 is identical to the arrangement of FIG. 3.

Referring now to FIG. 15, a further type of driving circuit andultrasonic motor combination is depicted. The ultrasonic motor isprovided with a pair of crystals 18812 and 18% having an electrode 190therebetween. Motor 45b further includes a rear portion 19% and lockingmeans in the form of a nut 19% for holding rear portion 191)), crystals188i; and 18% and electrode 19012 in compressed engagement withtransmission member 50b. Driving circuit 30b is coupled to motor 4512 bylines 2041) and line 2031). Line 2031) is electrically connected toelectrode 19012 while line 20412 is grounded and connected to rearportion 190)). This embodiment does not have a crystal detectorarrangement for sustaining the motor at' the desired frequency. Rather,the frequencies of oscillation of motor 451; are reflected back throughlines 204b and 2031) to driving circuit 301) where they are detected forthe purposes of controlling the frequency of the driving signal appliedto said motor for collector the vibrations thereof. Driving circuit 301)iricludes a transistor 20517.

The emitter 21612 of said transistor is connected through resistor 217bto ground. Resistor 217 is shunted by a capacitor 218!). The collecgor20617 of said transistor is connected through choke 207!) to variableresistor 19912, which in turnis connected to the power source. Thejunction between collector 206b and choke 20711 is connected throughcapacitor 215 to line 2041) and is connected to the primary winding20212 of transformer 21212, the other end of said primary winding beingconnected to line 2031;. The secondary of transformer 212b is connectedin parallel with a capacitor 214!) to definea tuned tank circuit. Saidparallelconnected circuit is connected between ground and the base 20%of the transistor. Said base is also connected through resistor 20812 toresistor 199, for biasing said base.

The power supply is connected to the normal A.C. 60'

Hz source through lines 34b and 36b, and in turn is applied to' theprimary winding 198b of transformer b. The secondary winding 196b ofsaid transformer is coupled between ground and a diode 19412. Theparallel combination of a capacitor l97b and resistor l93b is connectedbetween said diode and ground, resistor 1931) being tapped off andconnected to resistor 19%. Said power supply produces a half-waverectified signal, the value of capacitor 197)) being selected forminimum smoothing.

Driving circuit 30!) operates as follows. When switch 42b is closed, asurge of energy is applied to crystals l89b and 18817 and the motor 45bis set into oscillation. A signal representative of the frequencies ofoscillation of said motor is reflected back through lines 204b and 20312to the primary of transformer 212b. This signal is detected by' thetuned circuit defined by secondary winding 2l0b and capacitor 214b,which is tuned to the desired frequency of oscillation of the motor.Only the portion of said detected signal representative of said desiredfrequency is transmitted to base 20% to switch transistor 205b on andoff at an ultrasonic rate. When transistor 205); is on, the power signalfrom the power source, essentially in the form of a half-wave rectifiedsignal, is short circuited. When transistor 205b is off, the power.signal is applied through transformer primary winding 202b to theultrasonic motor. In this manner, a driving signal consisting of burstsof ultrasonic oscillations repeated at a sonic rate are applied to motor451) to produce bursts of ultrasonic vibrations repeated at a sonicrate.

Turning now to FIGS. 16 and 17, there is illustrated a shaving system200 which is described in greater detail in the co-pending patentapplication assigned to the assignee of the present invention, Ser. No.204,632, filed Dec. 3, I971, and for present purposes, it is sufficientto indicate that it includes an instrument means or handle means 25cadapted to be held by the user in a conventional manner, with adetachable shaving head or assembly 2210 containing a member or blade223c to be ultrasonically vibrated and mounted therein. Extending fromone end thereof is supply means l30c which supplies to the instrumentmeans 25c. power from generator or power means 300 having an electricalcord 1346 connected to a plug 132C adapted to be plugged into a standardelectrical outlet; i.e., 60 cycles per second. Switching means 400 onthe generator inthe ultrasonic transducer or motor 450 contained withinthe instrument casing or housing means 260 of the hand-held instrument250. The energy from the generator 300 is transmitted to the ultrasonicmotor by wires extending through the flexible conduit 520 of the supplymeans 320.

The complete assembly for use in the home includes the generating means300, for example, a transistorized driving circuit means capable ofproducing a driving signal consisting of bursts of electricaloscillation at a frequency in the ultrasonic range, as defined herein,repeated at a sonic rate herein defined. Driving circuits to obtain thedual frequency are discussed in detail with respect to FIGS. 3, l4 and15.

The ultrasonic energy available at the cutting edge 2250 of the blade2230 provides several beneficial results. It has been found that, byreason of the vibrations at the cutting edge 2250, which vibrations maybe in a substantially vertical plane; that is, in a plane perpendicularto the plane of the cutting edge 2250, the resistance of the blademember 2230 across the skin surface is very substantially reduced. Thefriction reduction effects and the cutting ease may be obtained by thevibrations having an elliptical, orbital, longitudinal or flexuralcomponent of motion at the cutting edge 2250. A possible explanation ofthis observed phenomenon is that the extremely high acceleration of thecutting edge 2250 of shaving member 2230 resulting from the vibrationscauses only a relatively small sliding friction to be present betweenthe engaged skin surface and the shaving member 2230. Thus, the dualfrequency provides a visible gross motion to the shaving member 2230 andsimultaneously imparts to the shaving member the acceleration forces toreduce the friction and successively subject the hair portions extendingfrom the skin to the cutting action of the cutting edge at a repetitionrate of from 15,000 to 500,000 times per second and thus provide acontinuous severing of the hairs at or adjacent to the surface of theskin.

The frequency of the vibrations at the free end portion of blade member2230 is in the range from 15 to 500 kilocycles per second, while theamplitude of the vibrations is selected within the range fromapproximately 0.0001 to 0.025 inch so as to ensure the introduction ofvibratory energy sufficient to perform the cutting of the hair particlesand maintain the friction reduction qualities. Simultaneously therewith,the convertermotor system functions by cyclically interrupting thevibratory motion to produce the buzzing or jiggling which indicates thatthe razor is operating.

Thus, the vibratory energy applied at a suitable frequency, to the bladeproduces vibratory motion of the molecular structure of such blade sothat the surface of blade 2230 is continuously maintained, while beingmoved relative to the hair, at a state of microscopic motion in theultrasonic range relative to the surface of the skin, whereby thefrictional resistance of movement of the shaving member 2230 to thesurface is determined by the kinetic coefficient of frictiontherebetween rather than by the substantially larger static coefficientof friction between the material of the shaving member 2230 and theskin. The ultrasonic shaving instrument 200 also permits a closer shaveto be obtained due to the inherent characteristics of a vibratory memberwhich when vibrated in the ultrasonic frequency range as herein definedwill vibrate with an acceleration of at least 1,000gs such that the timeof contact between the cutting edge 2250 and the surface of the skin isminimal even when a static force is applied by the user against theskin.

5 Due to the geometric configuration of the mounting of the blade 2230within the shaving head assembly 220, it is possible to obtain aflexural component of motion at the blade edge 2250 and at the same timethe physical vibration produced by the ultrasonic frequency producespeak accelerations in the shaving signed to function in conjunction withblade edge 2250 in effecting shaving. The ultrasonic vibrations areintroduced in a longitudinal direction, and due to the geometry of theshaving head assembly 2210, the vibrations are induced in blade 2230 ina plane substantially normal to the surface thereof.

CONCLUSION From the foregoing, it will be evident that the applicationof bursts of ultrasonic vibrations repeated at a sonic rate is effectiveto provide significantly improved results in many applications ofvibratory motion, only two of which have been herein illustrated by wayof example. It is well appreciated that the invention herein defined maybe employed in innumerable applications,

some of which presently exist in the form of low frequency applicationsand others in the form of high frequency applications, so that for thefirst time, the synergistic benefits of the combination of high and lowfrequency effects may be achieved.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in carrying out the above method andin the devices set forth without departing from the spirit and scope ofthe invention, it is intended that all matter contained in the abovedescription and shown in the accompanying drawings shall be interpretedas illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:

l. The method of performing work on an object, comprising the steps of:

A. positioning an applicator capable of physical vibration at anultrasonic frequency adjacent the object;

B. inducing vibrations in said applicator at a frequency in theultrasonic range of 10 KHz to 1,000 KHZ; and

C. modulating the ultrasonic frequency of said applicator at a sonicfrequency in the range of 10 Hz to 1,000 Hz to produce bursts ofultrasonic vibrations in said applicator repeated at said sonicfrequency.

2. The method as defined in claim 1, wherein said applicator islongitudinally vibrated.

3. The method as defined in claim 1, wherein said ultrasonic frequencyis in the range of 20 KHz to 60 KHZ.

4. The method as defined in claim 1, wherein said sonic frequency is inthe range of 10 Hz to 1,000 Hz.

5. The method as claimed in claim 1, wherein said applicator is in theform of a toothbrush.

6. The method as defined in claim 1, and further including the step ofengaging said applicator against the object.

7. The method of simultaneously applying a micromotion and amacro-motion to a surface, comprising the steps of:

A. generating ultrasonic vibrations in the working end of a handheldultrasonic motor to produce peak accelerations in said working end ofthe order of at least 1,000g; v

B. modulating the amplitude of ultrasonic vibrations at a sonic rate inthe range of 10 Hz to 1,000 Hz so as to produce bursts of ultrasonicvibration repeated at a sonic rate; and

C. simultaneously applying said working end against said surface in arelative moving relationship with respect thereto, whereby saidmicro-motion and macro-motion are transmitted thereto.

8. The method as defined in claim 7, wherein the width of each of saidbursts of ultrasonic vibration and the interval therebetween areessentially equal.

9. The method as defined in claim 7, wherein said working end is in theform of a toothbrush.

10. The method as defined in claim 7, wherein said working end islongitudinally vibrated.

11. The method of removing foreign matter, including plaque and othersurface deposits from teeth comprising the steps of:

A. positioning adjacent the teeth to be cleaned a surface capable ofsupporting and transmitting ultrasonic vibrations without damage to saidteeth;

B. vibrating said surface at an ultrasonic frequencyin the range f KHzand 500 KHz;

C. modulating said ultrasonic frequency vibrations of said surface at asonic frequency in the range of 10 Hz to 1,000 Hz to produce bursts ofultrasonic vibration repeated at a sonic frequency rate; and

D. moving said vibrating surface relative to said teeth such that itengages and removes the foreign deposits therefrom.

12. The method as defined in claim 11, wherein said surface is composedof a plastic material.

13. The method as defined in claim 11, wherein said 20 ultrasonicfrequency is in the range .of 20 KHz to 60 KHZ.

14. The method as defined in claim 11, including the step of providing afluid film' between said surface and said teeth, said ultrasonicvibrations being of an amplitude to produce a cavitational action insaid fluid film when said surface is displaced from said teeth.

15. The method as defined in claim 14, wherein said surface is in theform of a plurality of individual bristle elements such that theelements assume positions in which they are randomly divided betweenactual contact with and displacement from the surfaces of said teeth.

16. The method of removing foreign matter, including plaque and othersurface deposits from teeth by simultaneously applying a micro-motionand macromotion to the teeth surfaces, comprising the steps of:

A. generating ultrasonic vibrations in bristle elements I at the workingend of a hand-held ultrasonic motor;

B. amplitude modulating said ultrasonic vibrations at a sonic rate so asto produce bursts of ultrasonic vibrations repeated at a sonic rate; and

C. engaging said bristle elements against said teeth surfaces at arelative moving relationship.

17. The method as defined in claim 16, wherein each of said bursts ofultrasonic vibrations is of a width equal to the interval between saidbursts of ultrasonicvibration.

18. The method as defined in claim 16, including the further step ofproviding a fluid film at the teeth surfaces.

19. The method as defined in claim 18, wherein said motion of saidbristle elements is of an amplitude of vibration to produce acavitational action in said fluid film between said bristle elements andsaid teeth surfaces when said bristle elements are displaced therefrom.

20. The method as defined in claim 16, wherein said working end of saidhand-held ultrasonic motor in surrounding relation to said bristleelements is insulated, whereby the ultrasonic energy waves arriving atthe insulation will be almost totally reflected back into saidinstrument providing more energy available to the bris- I tle elementsto perform their work.

1. The method of performing work on an object, comprising the steps of:A. positioning an applicator capable of physical vibration at anultrasonic frequency adjacent the object; B. inducing vibrations in saidapplicator at a frequency in the ultrasonic range of 10 KHz to 1,000KHz; and C. modulating the ultrasonic frequency of said applicator at asonic frequency in the range of 10 Hz to 1,000 Hz to produce bursts ofultrasonic vibrations in said applicator repeated at said sonicfrequency.
 2. The method as defined in claim 1, wherein said applicatoris longitudinally vibrated.
 3. The method as defined in claim 1, whereinsaid ultrAsonic frequency is in the range of 20 KHz to 60 KHz.
 4. Themethod as defined in claim 1, wherein said sonic frequency is in therange of 10 Hz to 1,000 Hz.
 5. The method as claimed in claim 1, whereinsaid applicator is in the form of a toothbrush.
 6. The method as definedin claim 1, and further including the step of engaging said applicatoragainst the object.
 7. The method of simultaneously applying amicro-motion and a macro-motion to a surface, comprising the steps of:A. generating ultrasonic vibrations in the working end of a hand-heldultrasonic motor to produce peak accelerations in said working end ofthe order of at least 1,000g; B. modulating the amplitude of ultrasonicvibrations at a sonic rate in the range of 10 Hz to 1,000 Hz so as toproduce bursts of ultrasonic vibration repeated at a sonic rate; and C.simultaneously applying said working end against said surface in arelative moving relationship with respect thereto, whereby saidmicro-motion and macro-motion are transmitted thereto.
 8. The method asdefined in claim 7, wherein the width of each of said bursts ofultrasonic vibration and the interval therebetween are essentiallyequal.
 9. The method as defined in claim 7, wherein said working end isin the form of a toothbrush.
 10. The method as defined in claim 7,wherein said working end is longitudinally vibrated.
 11. The method ofremoving foreign matter, including plaque and other surface depositsfrom teeth comprising the steps of: A. positioning adjacent the teeth tobe cleaned a surface capable of supporting and transmitting ultrasonicvibrations without damage to said teeth; B. vibrating said surface at anultrasonic frequency in the range of 10 KHz and 500 KHz; C. modulatingsaid ultrasonic frequency vibrations of said surface at a sonicfrequency in the range of 10 Hz to 1,000 Hz to produce bursts ofultrasonic vibration repeated at a sonic frequency rate; and D. movingsaid vibrating surface relative to said teeth such that it engages andremoves the foreign deposits therefrom.
 12. The method as defined inclaim 11, wherein said surface is composed of a plastic material. 13.The method as defined in claim 11, wherein said ultrasonic frequency isin the range of 20 KHz to 60 KHz.
 14. The method as defined in claim 11,including the step of providing a fluid film between said surface andsaid teeth, said ultrasonic vibrations being of an amplitude to producea cavitational action in said fluid film when said surface is displacedfrom said teeth.
 15. The method as defined in claim 14, wherein saidsurface is in the form of a plurality of individual bristle elementssuch that the elements assume positions in which they are randomlydivided between actual contact with and displacement from the surfacesof said teeth.
 16. The method of removing foreign matter, includingplaque and other surface deposits from teeth by simultaneously applyinga micro-motion and macro-motion to the teeth surfaces, comprising thesteps of: A. generating ultrasonic vibrations in bristle elements at theworking end of a hand-held ultrasonic motor; B. amplitude modulatingsaid ultrasonic vibrations at a sonic rate so as to produce bursts ofultrasonic vibrations repeated at a sonic rate; and C. engaging saidbristle elements against said teeth surfaces at a relative movingrelationship.
 17. The method as defined in claim 16, wherein each ofsaid bursts of ultrasonic vibrations is of a width equal to the intervalbetween said bursts of ultrasonic vibration.
 18. The method as definedin claim 16, including the further step of providing a fluid film at theteeth surfaces.
 19. The method as defined in claim 18, wherein saidmotion of said bristle elements is of an amplitude of vibration toproduce a cavitational action in said fluiD film between said bristleelements and said teeth surfaces when said bristle elements aredisplaced therefrom.
 20. The method as defined in claim 16, wherein saidworking end of said hand-held ultrasonic motor in surrounding relationto said bristle elements is insulated, whereby the ultrasonic energywaves arriving at the insulation will be almost totally reflected backinto said instrument providing more energy available to the bristleelements to perform their work.